Plug-and-Play optical mouse doesn't work on Mac

[SilverLining]

Since I've upgraded to Leopord my USB drives don't mount properly. I've noticed that when my iPod is plugged in, it's not displayed as a device (this may be a different issue, though it was working before).

The problem I'm having now is that I have a plug-and-play mouse, but it's not picked up by my system. I've read about this a little and think the problem has to do with the "IOUSBMassStorageClass.kext" not being included as a plugin in this version.

Has anyone else experienced this or fixed this kind of issue before? I'm in the process of installing software updates now, so will see how I get on with this.

Thanks for your time!